Buoys are commonly used by commercial fishermen as markers for crab pots, nets, and for a wide variety of other uses. When the buoys are retrieved they typically are pulled along the surface of the water by a pole with a hook at the end, a grappling hook attached to a rope, or by other mechanisms. Oftentimes, buoys are constructed in such a way as to attempt to minimize the drag as the buoys are pulled along the surface of the water to make retrieval easier. For example, smooth surfaced glass sphere buoys are provided in nets, or in plastic containers having ribs, the nets and ribs providing turbulence which reduces the drag on the buoys. U.S. Pat. No. 3,906,565 shows an elongated buoy with a smooth surface having a plurality of longitudinal ribs thereon for reducing drag while also providing stability, and U.S. Pat. No. 4,995,842 shows an elongated buoy with a smooth surface having a plurality of square edged circumferential ribs for reducing drag.
Prior art buoys as described above do provide lower drag than conventional completely smooth surfaced buoys, however their ability to reduce drag has not previously been optimized. Therefore, there is a need to reduce drag even further, while still providing a buoy construction that is relatively easy to manufacture using commercially available techniques. Also, some of the prior art buoys described above have a tendency to spin during retrieval, which is undesirable since it can cause twisting or bunching of a line connected to the buoy or a line used for retrieval, and it is desirable to minimize such spinning.
According to the present invention, a buoy is provided--particularly designed for use by commercial fishermen--which has significantly less drag than prior art buoys. The buoy according to the invention also can be constructed so as to--it is believed--have minimal spin (and enhanced stability) during retrieval. Yet the buoy according to the invention can still be constructed in a relatively simple manner, using commercially available techniques.
The buoy according to the invention is a radical departure from the prior art buoys which have smooth surfaces with ribs--either in the form of nets or integrally molded ribs--extending outwardly from the smooth surfaces. According to the invention, a diameter variation, typically a diameter reduction, is provided at spaced locations along the longitudinal axis of the buoy extending from a first end to which a line is attached (e. g. which leads to a crab pot, etc.) to a second end. At the juncture of the different diameter portions, at each step reduction, a spoiler is provided on the larger diameter portion. The spoiler typically takes the form of a flipper with a ramp leading from the larger diameter portion to the flipper, and a substantially flat and radially extending surface of the flipper opposite the ramp.
The construction according to the invention is highly advantageous compared to conventional smooth walled buoys with nets or integral ribs for a number of reasons. The step-down construction provides a greater distance from the top of the spoiler (flipper) to the "downstream" buoy sidewall which enhances the spoiling action. Increasing the height of the spoiler so that it extended from a smooth sidewall the same amount would not be nearly as effective since this would also increase the size of the ramp leading from the upstream wall of the buoy to the spoiler, which in turn would add drag. The construction according to the invention has a negligible introduction of drag on the ramp side, but a maximum spoiling effect with a relatively large drop on the "downstream" end.
The ramp arrangement leading from the buoy sidewall to the flipper also is advantageous compared to a square rib extending from a smooth sidewall, or a rib that is rounded at both the "upstream" and "downstream" ends thereof. In the square rib construction the "upstream" edge adds drag, while in the double rounded construction, the "downstream" rounded portion does not produce as effective a spoiling action. Therefore the ramp and flipper configuration alone, according to the invention, can produce significant reduction in drag.
Overall, the buoy construction according to the present invention can achieve about a 50% reduction, or more, in drag compared to prior art constructions if the buoy is being pulled along the surface of the water at a speed of about 6-8 knots (a typical speed for commercial fishing buoy retrieval operations). Further, by providing a plurality of longitudinal ribs spaced around the circumference of the buoy, it is believed possible to reduce spinning and provide enhanced stability during retrieval.
According to one aspect of the present invention, a low drag buoy is provided comprising the following components: A buoyant body having first and second ends spaced from each other along a longitudinal axis, the body having the general configuration of a body of revolution (e.g. sphere, cylinder, ovoid, or the like). An end structure at the first end allowing connection of the first end to a line. The body having a plurality of different diameter portions between the first and second ends, a step reduction in diameter being provided at a juncture between each of the different diameter portions moving from the first end to the second end. And a spoiler provided on the larger diameter portion at each juncture. Each of the spoilers preferably comprises a flipper extending circumferentially outwardly from the larger diameter portion at each juncture, and a ramp surface leading from the body to the flipper from the first end toward the second end, the flipper having a substantially flat and radially extending surface opposite the ramp.
The ramp surface preferably has an angle of inclination of about 20-60 degrees (most desirably about 30-45 degrees) with respect to the longitudinal axis. While the ramp surface is preferably planar, it may be slightly radiused. Particularly good results are achieved when the flipper extends outwardly from the body about 0.04-0.08 inches (most, desirably about 0.062 inches), where the step reduction at each of the junctures, not counting the flipper, is about 0.1-0.125 inches (so that the diameter of the body at a juncture decreases about 0.2-0.25 inches), and where the angle of inclination is about 45.degree.. The junctures with step reductions are typically provided about every 3-6 (e.g. 4-5) inches along the longitudinal axis.
The body of revolution configuration of the body may take a variety of different forms. For example, after at least one of the step reductions the diameter of the body may gradually increase so that it is larger than the larger diameter portion at the at least one step reduction (that is the body having a generally spherical or ovoid shape). Alternatively, the diameter of the body may be consistently reduced at each juncture and then between junctures from the first end to the second end thereof (that is the body having a generally cylindrical shape). Rather than having high elongation, the body may have a length along the longitudinal axis, and a maximum diameter, such that the length is about 15-50% greater than the maximum diameter.
The low drag buoy according to the invention also may further comprise a plurality of longitudinal ribs, extending substantially parallel to the longitudinal axis, disposed on the body and upstanding therefrom, which may provide reduced spinning, and increased stability, of the buoy if pulled along the water surface from the first end of the body. The end structure at the first end typically comprises a substantially conical cap integral with the body, and a generally planar ear extending outwardly from the substantially conical cap, and an opening provided in the ear generally perpendicular to the longitudinal axis. Typically no end structure is provided at the second end of the buoy.
According to another aspect of the present invention, a low drag buoy is provided comprising the following elements: A varying diameter body of buoyant material and having first and second ends spaced from each other along a longitudinal axis, the body having the general configuration of a body of revolution (e.g. cylinder, sphere or ovoid). An end structure at the first end allowing connection of the first end to a line. And a plurality of flippers provided along the longitudinal axis of the body, each flipper extending circumferentially outwardly from the body, and a ramp surface leading from the body to each of the flippers from the first end toward the second end, and each of the flippers having a substantially flat and radially extending surface opposite the ramp. The details of the ramp surface, and the details of the other components, may be as described above.
It is the primary object of the present invention to provide a low drag buoy, particularly one with good stability during retrieval. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.